Generally, the industry of semiconductor manufacturing involves highly complex techniques for fabricating integrating circuits using semiconductor materials that are layered and patterned onto a substrate, such as silicon. An integrated circuit is typically fabricated from a plurality of reticles. Generation of reticles and subsequent optical inspection of such reticles have become standard steps in the production of semiconductors. The fabrication of semiconductor devices, such as logic and memory devices, typically includes processing a semiconductor wafer using a large number of semiconductor fabrication processes with multiple reticles to form various features and multiple levels of the semiconductor devices. Multiple semiconductor devices may be fabricated in an arrangement on a single semiconductor wafer and then separated into individual semiconductor devices. The wafer position with respect to the reticle is a significant factor that affects fabrication results.
After wafer is fabricated, it may be inspected for defects or certain features of the wafer may be measured. Likewise, reticles may be inspected and reticle features measured. One factor is the ability to accurately report a defect's or measurement location.
Lithography and inspection systems both have a need for accurate positioning and position detection systems.